We have found that B-alkyl-9-borabicyclo (3.3.1) nonanes (9-BBN) reduce aldehydes and ketones to alcohols under remarkably mixed conditions. For example, benzaldehyde is reduced in 30 minutes at room temperature. The corresponding trialkylborane does not effect complete reduction of benzaldehyde in 24 hours at 65 degrees. This large rate of acceleration makes feasible the use of B-alkyl-9-BBN derivatives as mild and selective reducing agents. Furthermore, asymmetric B-alkyl-9-BBN groups induce a high degree of optical activity into the alcoholic product. Thus benzaldehyde-alpha-d gives benzyl-alpha-d alcohol which is 84-90% optically pure. Since the starting olefin for the B-alkyl-9-BBN was only 92% optically pure, the results indicate an essentially quantitative asymmetric induction. The enantioselectivity which we observe is far superior to other chemical reductions and approaches that achieved by enzymes. It is anticipated that organoboranes containing the proper optically-active groups will reduce a wide variety of aldehydes and ketones with a high degree of asymmetric induction. Functional groups such as esters, nitriles and epoxides, which are not known to react with organoboranes, should not interfere with ketone reduction. It may be possible to reduce imines, thus opening a route to optically-active amines and perhaps amino-acids. The use of organoboranes for resolution of ketones, for stereoselective reductions, and as a protecting group for olefins will be investigated. Important factors contributing to the selectivity and mechanism of the reduction will be elucidated.